1.作用与语法描述
作用: 正则表达式是使用指定字符串来描述、匹配一系列符合某个句法规则的字符串。许多程序设计语言都支持利用正则表达式进行字符串操作。MongoDB 使用 $regex 操作符来设置匹配字符串的正则表达式。
语法一
{ <field>: { $regex: /pattern/, $options: '<options>' } } { <field>: { $regex: 'pattern', $options: '<options>' } } { <field>: { $regex: /pattern/<options> } }
语法二
{ <field>: /pattern/<options> }
2.案例演示
假设MongoDB中存放了我们OrderService服务的消息信息,其数据如下:
(以下为演示所用到的9个文档)
{ "_id" : ObjectId("5d305b1c4857fc49c0c14c81"), "order" : "QQ00001", "data" : "\"<?xml version='1.0' encoding='UTF-8'?><Response service=\\\"OrderService\\\"><Head>ERR</Head><ERROR>重复下单</ERROR></Response>\"" }, { "_id" : ObjectId("5d305b3b4857fc49c0c14c82"), "order" : "QQ00001", "data" : "\"<?xml version='1.0' encoding='UTF-8'?><Response service=\\\"OrderService\\\"><Head>ERR</Head><ERROR>重复下单</ERROR></Response>\"" }, { "_id" : ObjectId("5d305b404857fc49c0c14c83"), "order" : "QQ00002", "data" : "\"<?xml version='1.0' encoding='UTF-8'?><Response service=\\\"OrderService\\\"><Head>ERR</Head><ERROR>重复下单</ERROR></Response>\"" }, { "_id" : ObjectId("5d305b454857fc49c0c14c84"), "order" : "QQ00002", "data" : "\"<?xml version='1.0' encoding='UTF-8'?><Response service=\\\"OrderService\\\"><Head>ERR</Head><ERROR>重复下单</ERROR></Response>\"" }, { "_id" : ObjectId("5d305b4b4857fc49c0c14c85"), "order" : "QQ00003", "data" : "\"<?xml version='1.0' encoding='UTF-8'?><Response service=\\\"OrderService\\\"><Head>ERR</Head><ERROR>重复下单</ERROR></Response>\"" }, { "_id" : ObjectId("5d305b4f4857fc49c0c14c86"), "order" : "QQ00003", "data" : "\"<?xml version='1.0' encoding='UTF-8'?><Response service=\\\"OrderService\\\"><Head>ERR</Head><ERROR>重复下单</ERROR></Response>\"" }, { "_id" : ObjectId("5d305bb74857fc49c0c14c87"), "order" : "QQ00003", "data" : "\"<?xml version='1.0' encoding='UTF-8'?><Response service=\\\"OrderService\\\"><Head>OK</Head><Body><OrderResponse filter_mmm=\\\"2\\\" destcity=\\\"shenzheng\\\" origincode=\\\"QQ0003\\\" /></Body></Response>\"" }, { "_id" : ObjectId("5d305bd14857fc49c0c14c88"), "order" : "QQ00002", "data" : "\"